Package org.axonframework.messaging.eventhandling.annotation

Class AnnotatedEventHandlingComponent<T>

java.lang.Object
org.axonframework.messaging.eventhandling.annotation.AnnotatedEventHandlingComponent<T>
Type Parameters:
T - The type of the annotated event handler.
All Implemented Interfaces:
DescribableComponent, MessageHandler, EventHandler, EventHandlingComponent
public class AnnotatedEventHandlingComponent<T> extends Object implements EventHandlingComponent
Adapter that turns classes with EventHandler annotated methods into a EventHandlingComponent.

Each annotated method is subscribed as an EventHandler at the EventHandlingComponent with the event name specified by the parameter of that method.

Since:
5.0.0
Author:
Mateusz Nowak

  • Constructor Details

    • AnnotatedEventHandlingComponent

      public AnnotatedEventHandlingComponent(@Nonnull T annotatedEventHandler, @Nonnull ParameterResolverFactory parameterResolverFactory, @Nonnull HandlerDefinition handlerDefinition, @Nonnull MessageTypeResolver messageTypeResolver, @Nonnull EventConverter converter)
      Wraps the given annotatedEventHandler, allowing it to be subscribed to an EventSink as an EventHandlingComponent.
      Parameters:
      annotatedEventHandler - The object containing the EventHandler annotated methods.
      parameterResolverFactory - The strategy for resolving handler method parameter values.
      handlerDefinition - The handler definition used to create concrete handlers.
      messageTypeResolver - The MessageTypeResolver resolving the names for EventMessages.
      converter - The converter to use for converting the payload of the event to the type expected by the handling method.

  • Method Details

    • handle

      @Nonnull public MessageStream.Empty<Message> handle(@Nonnull EventMessage event, @Nonnull ProcessingContext context)
      Description copied from interface: EventHandler
      Handles the given event within the given context.

      The result of handling is an empty stream.

      Specified by:
      handle in interface EventHandler
      Parameters:
      event - The event to handle.
      context - The context to the given event is handled in.
      Returns:
      An empty stream containing nothing.

    • supportedEvents

      public Set<QualifiedName> supportedEvents()
      Description copied from interface: EventHandlingComponent
      All supported events, referenced through a QualifiedName.
      Specified by:
      supportedEvents in interface EventHandlingComponent
      Returns:
      All supported events, referenced through a QualifiedName.

    • sequenceIdentifierFor

      @Nonnull public Object sequenceIdentifierFor(@Nonnull EventMessage event, @Nonnull ProcessingContext context)
      Description copied from interface: EventHandlingComponent
      Returns the sequence identifier for the given event. When two events have the same sequence identifier (as defined by their equals method), they will be executed sequentially. Important: All EventHandlers for the same QualifiedName within a single EventHandlingComponent must return the same sequence identifier for a given event. Mixing different sequence identifiers within the scope of a single EventHandlingComponent is not supported and may lead to undefined behavior.
      Specified by:
      sequenceIdentifierFor in interface EventHandlingComponent
      Parameters:
      event - The event for which to get the sequencing identifier.
      context - The processing context in which the event is being handled.
      Returns:
      A sequence identifier for the given event.

    • describeTo

      public void describeTo(@Nonnull ComponentDescriptor descriptor)
      Description copied from interface: DescribableComponent
      Describe the properties of this DescribableComponent with the given descriptor.

      Components should call the appropriate describeProperty methods on the descriptor to register their properties. The descriptor is responsible for determining how these properties are formatted and structured in the final output.

      Best Practices: As a general rule, all relevant fields of a DescribableComponent implementation should be described in this method. However, developers have discretion to include only the fields that make sense in the context. Not every field may be meaningful for description purposes, especially internal implementation details. Furthermore, components might want to expose different information based on their current state. The final decision on what properties to include lies with the person implementing the describeTo method, who should focus on providing information that is useful for understanding the component's configuration and state.

      Example implementation: 

       public void describeTo(ComponentDescriptor descriptor) {
     descriptor.describeProperty("name", this.name);
     descriptor.describeProperty("enabled", this.enabled);
     descriptor.describeProperty("configuration", this.configuration); // A nested component
     descriptor.describeProperty("handlers", this.eventHandlers);      // A collection
 }
      Specified by:
      describeTo in interface DescribableComponent
      Parameters:
      descriptor - The component descriptor to describe this DescribableComponentn its properties in.